Flexible display panel and method of bending the same

ABSTRACT

A flexible display panel includes a display area to display an image, and a non-display area disposed outside the display area. The non-display area includes a first portion and a second portion. The first portion extends from the display area, and includes a support layer disposed on a flexible substrate. The second portion extends from the first portion, and is bent from a plane of the first portion. A property of a material of the support layer in the first portion is different than the property of the material of the support layer in the second portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2016-0121691, filed on Sep. 22, 2016, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

Exemplary embodiments relate to display technology, and, moreparticularly, to flexible display panels and methods of bending thesame.

Discussion

Display devices have become iconographies of modern informationconsuming societies. Whether in the form of a cellular phone, consumerappliance, portable computer, television, or the like, aesthetic andergonomic appeal are as much design considerations as display qualityand overall performance. As such, greater attention is being directedtowards developing display devices with minimal to no bezelconfigurations. Flexible display panels capable of permanent deformation(e.g., bending) in areas outlying a display area, and, thereby, capableof reducing the planar surface area of these outlying areas, are gainingtraction at least because such configurations also enable peripheralcircuitry to remain proximate to the display area. It is noted, however,that as the bend radius of an outlying area decreases, an increasingamount of stress is applied to the bending area. This increase in stressmay increase resistivity in and reduce reliability of, for example,signal lines extending between the display area and the peripheralcircuitry configured to drive pixels of the display area. A need,therefore, exists for efficient, cost-effective techniques enablingflexible display panels to be permanently deformed at relatively smallbend radii, but maintain sufficient levels of performance andreliability.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the inventive concept,and, therefore, it may contain information that does not form the priorart that is already known to a person of ordinary skill in the art.

SUMMARY

One or more exemplary embodiments provide flexible display panelscapable of permanent, reliable deformation of outlying areas peripheralto a display area.

One or more exemplary embodiments provide flexible apparatuses capableof permanent, reliable deformation of outlying areas peripheral to anactive area.

One or more exemplary embodiments provide flexible apparatuses capableof permanent, reliable deformation of first areas peripheral to secondareas.

One or more exemplary embodiments provide methods of bending flexibledisplay panels that reduces stress in bending areas of the flexibledisplay panels.

One or more exemplary embodiments provide methods of bending flexibleapparatuses that reduces stress in bending areas of the flexibleapparatuses.

Additional aspects will be set forth in the detailed description whichfollows, and, in part, will be apparent from the disclosure, or may belearned by practice of the inventive concept.

According to one or more exemplary embodiments, a flexible display panelincludes a display area to display an image, and a non-display areadisposed outside the display area. The non-display area includes a firstportion and a second portion. The first portion extends from the displayarea, and includes a support layer disposed on a flexible substrate. Thesecond portion extends from the first portion, and is bent from a planeof the first portion. A property of a material of the support layer inthe first portion is different than the property of the material of thesupport layer in the second portion.

According to one or more exemplary embodiments, a method of bending aflexible display panel includes: altering, via thermal deformation, aproperty of a material of a support layer disposed on a flexiblesubstrate in a non-display area of the flexible display panel; andbending, after altering the property, a portion of the non-display areafrom a plane of a display area of the flexible display panel, thenon-display area extending from the display area.

According to one or more exemplary embodiments, a flexible apparatusincludes an active area, and an inactive area disposed outside theactive area. The inactive area includes a first portion and a secondportion. The first portion extends from the active area, and includes asupport layer disposed on a flexible substrate. The second portionextends from the first portion, and is bent from a plane of the firstportion. A property of a material of the support layer in the firstportion is different than the property of the material of the supportlayer in the second portion.

According to one or more exemplary embodiments, a flexible apparatusincludes a first area, and a second area disposed outside the activearea. The second area includes a first portion and a second portion. Thefirst portion extends from the first area, and includes a support layerdisposed on a flexible substrate. The second portion extends from thefirst portion, and is bent from a plane tangent a surface of the firstportion. A property of a material of the support layer in the firstportion is different than the property of the material of the supportlayer in the second portion.

According to one or more exemplary embodiments, a method of bending aflexible apparatus includes: altering, via thermal deformation, aproperty of a material of a support layer disposed on a flexiblesubstrate in an inactive area of the flexible display panel; andbending, after altering the property, a portion of the inactive areafrom a plane of an active area of the flexible apparatus, the inactivearea extending from the active area.

According to one or more exemplary embodiments, a method of bending aflexible apparatus includes: altering, via thermal deformation, aproperty of a material of a support layer disposed on a flexiblesubstrate in a first area of the flexible display panel; and bending,after altering the property, a portion of the first area from a plane ofa second area of the flexible apparatus, the second area extending fromthe first area.

The foregoing general description and the following detailed descriptionare exemplary and explanatory and are intended to provide furtherexplanation of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the inventive concept, and are incorporated in andconstitute a part of this specification, illustrate exemplaryembodiments of the inventive concept, and, together with thedescription, serve to explain principles of the inventive concept.

FIG. 1 is a perspective view of a flexible display panel in a non-bentstate, according to one or more exemplary embodiments.

FIG. 2 is a perspective view of the flexible display panel of FIG. 1 ina first bent state, according to one or more exemplary embodiments.

FIG. 3 is a cross-sectional view of the flexible display panel of FIG. 1taken along sectional line III-III′, according to one or more exemplaryembodiments.

FIGS. 4A and 4B are cross-sectional views of the flexible display panelof FIG. 1 taken along sectional line III-III′ in a second bent state,according to various exemplary embodiments.

FIG. 5 is an equivalent circuit diagram of a pixel of the flexibledisplay panel of FIG. 1, according to one or more exemplary embodiments.

FIG. 6 is a flowchart of a process for forming a flexible display panelwith at least one bent portion, according to one or more exemplaryembodiments.

FIG. 7 is a flowchart of a process for bending a flexible display panelvia a hot wire bending technique, according to one or more exemplaryembodiments.

FIGS. 8A, 8B, 8C, and 8D are partial perspective views of a flexibledisplay panel at various stages of being bent via a hot wire bendingtechnique, according to one or more exemplary embodiments.

FIGS. 9A, 9B, and 9C are partial cross-sectional views of various hotwire configurations, according to one or more exemplary embodiments.

FIG. 10 illustrates material property alterations in a layer of aflexible display panel caused, at least in part, by a hot wire bendingtechnique, according to one or more exemplary embodiments.

FIG. 11 is a flowchart of a process for bending a flexible display panelvia a hot press bending technique, according to one or more exemplaryembodiments.

FIGS. 12A and 12B schematically illustrate various stages of a hot pressbending technique, according to one or more exemplary embodiments.

FIGS. 13A, 13B, and 13C schematically illustrate various hot pressconfigurations, according to various exemplary embodiments.

FIGS. 14A and 14B schematically illustrate a flexible display panel atvarious stages of a hot press bending technique, according to one ormore exemplary embodiments.

FIGS. 15A and 15B schematically illustrate a flexible display panel atvarious stages of a hot press bending technique, according to one ormore exemplary embodiments.

FIGS. 16A and 16B schematically illustrate a flexible display panel atvarious stages of being bent, according to one or more exemplaryembodiments.

FIG. 17 is a flowchart of a process for bending a flexible displaypanel, according to one or more exemplary embodiments.

FIGS. 18A and 18B schematically illustrate a flexible display panel atvarious stages of being bent, according to one or more exemplaryembodiments.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments. It is apparent, however,that various exemplary embodiments may be practiced without thesespecific details or with one or more equivalent arrangements. In otherinstances, well-known structures and devices are shown in block diagramform in order to avoid unnecessarily obscuring various exemplaryembodiments.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail ofvarious exemplary embodiments. Therefore, unless otherwise specified,the features, components, modules, layers, films, panels, regions,and/or aspects of the various illustrations may be otherwise combined,separated, interchanged, and/or rearranged without departing from thedisclosed exemplary embodiments. Further, in the accompanying figures,the size and relative sizes of layers, films, panels, regions, etc., maybe exaggerated for clarity and descriptive purposes. When an exemplaryembodiment may be implemented differently, a specific process order maybe performed differently from the described order. For example, twoconsecutively described processes may be performed substantially at thesame time or performed in an order opposite to the described order.Also, like reference numerals denote like elements.

When an element or layer is referred to as being “on,” “connected to,”or “coupled to” another element or layer, it may be directly on,connected to, or coupled to the other element or layer or interveningelements or layers may be present. When, however, an element or layer isreferred to as being “directly on,” “directly connected to,” or“directly coupled to” another element or layer, there are no interveningelements or layers present. Further, the D1-axis, the D2-axis, and theD3-axis are not limited to three axes of a rectangular coordinatesystem, and may be interpreted in a broader sense. For example, theD1-axis, the D2-axis, and the D3-axis may be perpendicular to oneanother, or may represent different directions that are notperpendicular to one another. For the purposes of this disclosure, “atleast one of X, Y, and Z” and “at least one selected from the groupconsisting of X, Y, and Z” may be construed as X only, Y only, Z only,or any combination of two or more of X, Y, and Z, such as, for instance,XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various elements, components, regions, layers, and/or sections,these elements, components, regions, layers, and/or sections should notbe limited by these terms. These terms are used to distinguish oneelement, component, region, layer, and/or section from another element,component, region, layer, and/or section. Thus, a first element,component, region, layer, and/or section discussed below could be termeda second element, component, region, layer, and/or section withoutdeparting from the teachings of the present disclosure.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” “overlapping,” and the like, may be used herein for descriptivepurposes, and, thereby, to describe one element or feature'srelationship to another element(s) or feature(s) as illustrated in thedrawings. Spatially relative terms are intended to encompass differentorientations of an apparatus in use, operation, and/or manufacture inaddition to the orientation depicted in the drawings. For example, ifthe apparatus in the drawings is turned over, elements described as“below” or “beneath” other elements or features would then be oriented“above” the other elements or features. Thus, the exemplary term “below”can encompass both an orientation of above and below. Furthermore, theapparatus may be otherwise oriented (e.g., rotated 90 degrees or atother orientations), and, as such, the spatially relative descriptorsused herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof.

Various exemplary embodiments are described herein with reference tosectional illustrations that are schematic illustrations of idealizedexemplary embodiments and/or intermediate structures. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should not beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the drawings are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

According to one or more exemplary embodiments, a flexible display panelrefers to a display panel having various degrees of flexibility, and mayhave the same meaning as a bendable display panel, a rollable displaypanel, a foldable display panel, a twistable display panel, and thelike.

Although various exemplary embodiments are described with respect toflexible organic light emitting display panels, it is contemplated thatvarious exemplary embodiments are also applicable to other flexibledisplay panels, such as flexible liquid crystal display panels, flexibleinorganic electroluminescent display panels, flexible field emissiondisplay panels, flexible plasma display panels, flexible electrophoreticdisplay panels, flexible electrowetting display panels, and the like.Further, although various exemplary embodiments are described withrespect to flexible display panels incorporated as part of a mobilephone, exemplary embodiments are also applicable to other electronicdevices incorporating a flexible display panel, such as televisions,media players, notebook computers, gaming devices, tablets, monitors,navigational aids, pendant devices, billboards, wrist watches,headphones, earpiece devices, consumer appliances, etc. It is alsocontemplated that exemplary embodiments are applicable to configuringother flexible devices, such as configuring flexible light receivingcomponents of, for instance, photovoltaic cells, configuring flexibletouch screen devices, etc.

FIG. 1 is a perspective view of a flexible display panel in a non-bentstate, according to one or more exemplary embodiments. FIG. 2 is aperspective view of the flexible display panel of FIG. 1 in a first bentstate, according to one or more exemplary embodiments. FIG. 3 is across-sectional view of the flexible display panel of FIG. 1 taken alongsectional line III-III′, according to one or more exemplary embodiments.FIG. 4A is a cross-sectional view of the flexible display panel of FIG.1 taken along sectional line III-III′ in a second bent state, accordingto one or more exemplary embodiments.

Referring to FIGS. 1-3 and 4A, flexible display panel 100 includesflexible substrate TFS upon which display panel layer DP, touch screenlayer TS, and anti-reflection layer POL may be disposed. To this end,flexible substrate TFS may be disposed on support layer BF, which mayalso be referred to as a backfilm layer. One or more components, such asintegrated circuit IC and flexible printed circuit board FPCB, may becoupled to (or otherwise formed on) flexible substrate TFS. To this end,flexible display panel 100 may also include bending protection layerBPL. Although specific reference will be made to this implementation, itis also contemplated that flexible display panel 100 may embody manyforms and include multiple and/or alternative components. For example,it is contemplated that one or more components of flexible display panel100 may be combined, formed as part of separate structures, etc.

For descriptive convenience, a surface of flexible display panel 100 onwhich an image may be perceived, will be referred to as first (or front)surface SF1. An opposite surface of flexible display panel 100 will bereferred to as second (or back) surface SF2.

According to one or more exemplary embodiments, flexible display panel100 may be incorporated as part of an electronic device (not shown),such as a mobile phone. In this manner, the electronic device mayinclude a housing (not illustrated) configured to support at least aportion of flexible display panel 100 and one or more other componentsof the electronic device, such as one or more drivers, which may beelectrically connected to (or interface with) flexible display panel 100via, for instance, integrated circuit IC and/or flexible printed circuitboard FPCB. The housing may be formed of any suitable material, such asplastics, glasses, ceramics, composites, metals, or other materials, ora combination thereof. As such, the housing may have a unibodyconfiguration or may be formed from multiple structures.

For descriptive and illustrative convenience, flexible display panel 100will be described as a flexible organic light emitting diode (OLED)display panel, however, exemplary embodiments are not limited thereto orthereby. In this manner, display panel layer DP may be an OLED displaypanel layer, or any other suitable display panel layer. As seen in FIGS.3 and 4A, flexible display panel 100 may include touch sensor layer TS.The touch sensor layer TS may be formed as any suitable touch sensitivelayer, such as a capacitive touch sensor layer, a resistive touch sensorlayer, a surface acoustic wave touch sensor layer, an infrared touchsensor layer, a near field imaging touch sensor layer, etc. As such,flexible display panel 100 may provide a touch screen feature. Flexibledisplay panel 100 may also include anti-reflection layer POL, which maybe configured to darken an image displayed via display panel layer DP,manage reflection of ambient light, suppress glare, and/or the like. Inthis manner, anti-reflection layer POL may protect display panel layerDP from ambient light or at least reduce the effect of ambient light onthe display quality of display panel layer DP.

Although illustrated as separate layers, touch sensor layer TS and/oranti-reflection layer POL may be incorporated as part of another layerof flexible display panel 100, such as part of display panel layer DP.For instance, touch sensor layer TS may be formed on a thin-filmencapsulation layer (not shown) of display panel layer DP that covers,for instance, an electroluminescence layer (not illustrated) of displaypanel layer DP configured to emit light as part of displaying an imagevia flexible display panel 100. It is also contemplated that at leastone of touch sensor layer TS and anti-reflection layer POL may beprovided as a separate module coupled to display panel layer DP.

According to one or more exemplary embodiments, flexible display panel100 is a deformable (e.g., bendable, foldable, flexible, etc.) displaypanel including flexible substrate TFS on which display panel layer DPis disposed. Flexible substrate TFS may be formed of a thermosetmaterial, however, exemplary embodiments are not limited thereto orthereby. In other words, flexible substrate TFS may be formed of anysuitable material. For instance, flexible substrate TFS may be formed ofpolyimide (PI) having a decomposition temperature around 452° C. whenheat is continuously applied and around 704° C. when heat is applied inrelatively short bursts. In one or more exemplary embodiments, thematerial configuration of flexible substrate TFS may exhibit a highermelting and/or sublimating temperature than a material configuration ofsupporting layer BF.

Display panel layer DP is configured to display an image by combininglight from pixels (e.g., pixel PXL) disposed in display area DA offlexible display panel 100. Display area DA may also correspond to anactive area, such as an active area of display panel layer DP, an activearea of touch sensing layer TS, etc. In this manner, the active area maybe a region in which a function of flexible display panel 100 isprovided to a user, such as a display function, a touch sensingfunction, etc. For descriptive and illustrative convenience, displayarea DA and the active area may be referred to as display area DA.Pixels PXL may be arranged in any suitable formation, such as a matrixformation, in at least the display area DA. One or more non-displayareas (e.g., non-display areas NDA1, NDA2, NDA3, and NDA4) may bedisposed outside of display area DA. The one or more non-display areasmay also correspond to an inactive area, such as an inactive area ofdisplay panel layer DP, an inactive area of touch sensing layer TS, etc.In this manner, the inactive area may be a region in which the functionprovided in display area DA is not provided. For descriptive andillustrative convenience, the one or more non-display areas (e.g.,non-display areas NDA1, NDA2, NDA3, and NDA4) and the inactive area maybe referred to as non-display areas.

The one or more non-display areas may include first non-display areaNDA1, second non-display area NDA2, third non-display area NDA3, andfourth non-display area NDA4. It is noted that first to fourthnon-display areas NDA1 to NDA4 may surround display area DA, but are atleast disposed outside of (or adjacent to) display area DA. As seen inFIGS. 1 and 2, first non-display area NDA1 and second non-display areaNDA2 are spaced apart from one another and face one another whenflexible display panel 100 is viewed in a plan view, e.g., when viewedin direction D3. To this end, third non-display area NDA3 and fourthnon-display area NDA4 may be respectively adjacent to first non-displayarea NDA1 and second non-display area NDA2. Third non-display area NDA3and fourth non-display area NDA4 may be spaced apart from one anotherand face one another when flexible display panel 100 is viewed in a planview. One or more portions of first to fourth non-display areas NDA1 toNDA4 may be covered by an opaque masking material (not illustrated),such as a light blocking layer formed of, for instance, a polymerincluding carbon black pigmentation, a layer of opaque metal material,and/or the like. The light blocking layer may help conceal componentsdisposed in association with at least one of first to fourth non-displayareas NDA1 to NDA4.

According to one or more exemplary embodiments, pixels PXL may bedriven, at least in part, via at least one of a main driver (not shown),a gate driver (not illustrated), a data driver (not shown), and a powersource (not illustrated). At least one of the main driver, the gatedriver, the data driver, and the power source may be coupled to (orintegrated as part of) flexible printed circuit board FPCB and/orintegrated circuit IC.

For instance, the data driver and/or the gate driver may be coupled to asurface of a non-display area of flexible display panel 100 via achip-on-plastic (COP) technique or a chip-on-film (COF) technique (thefilm being, for example, a flexible film), and the main driver may bedisposed on flexible printed circuit board FPCB. In one or moreexemplary embodiments, a COP technique may include mounting anintegrated circuit forming a driving circuit (e.g., the data driver, thegate driver, etc.) on flexible substrate TFS via a conductive film (notillustrated), such as an anisotropic conductive film. A COF techniquemay, for example, include mounting an integrated circuit forming adriving circuit (e.g., the data driver, the gate driver, etc.) on a film(not shown), the film being utilized to couple flexible printed circuitboard FPCB to flexible substrate TFS. It is noted that the main drivermay be connected to the data driver and the gate driver via signal linesSL. Flexible printed circuit board FPCB may include a flexible printedcircuit and a multilayer printed circuit board; however, exemplaryembodiments are not limited thereto or thereby. As another example, thedata driver and/or the gate driver may be coupled to a non-display areaof flexible display panel 100 via a tape-automated bonding (TAB) method.In this manner, the main driver, the gate driver, and the data drivermay be disposed on flexible printed circuit board FPCB, and, thereby, beelectrically connected to one another. For instance, flexible printedcircuit board FPCB may include a tape carrier package (TCP) on which thedata driver and/or the gate driver may be mounted, and a multilayerprinted circuit board on which the main driver may be mounted. Themultilayer printed circuit board may be connected to the TCP. Also, thepower source (e.g., an external power source) may be connected to themain driver.

According to one or more exemplary embodiments, signal lines SL mayextend between pixels PXL and at least one of the main driver, the gatedriver, the data driver, and the power source. It is also contemplatedthat one or more of signal lines SL may be connected to one or morepixels PXL, but not connected to at least one of the main driver, thegate driver, the data driver. In this manner, signal lines SL maygenerally be disposed in at least one of first to fourth non-displayareas NDA1 to NDA4 and extend into display area DA. Although signallines SL are illustrated as crossing bending axis BX at various angles,it is contemplated that signal lines SL may extend across bending axisBX in first direction D1, e.g., in a direction perpendicular to bendingaxis BX. Further, signal lines SL may be connected to or form signallines disposed in display area DA, such as gate lines GL, data lines DL,and data voltage lines DVL. As such, pixels PXL may display an imagebased on signals received via the main driver, the gate driver, the datadriver, and the power source. An equivalent circuit of a representativepixel is described in more detail in association with FIG. 5.

FIG. 5 is an equivalent circuit diagram of a pixel of the flexibledisplay panel of FIG. 1, according to one or more exemplary embodiments.It is noted that pixel PXL of FIG. 5 is representative of the variouspixels of flexible display panel 100.

With continued reference to FIG. 1, pixel PXL may include pixel circuit501 connected to gate line GL extending in first direction D1, data lineDL extending in second direction D2, and driving voltage line DVL alsoextending in second direction D2. Second direction D2 may cross firstdirection D1. To this end, first and second directions D1 and D2 maycross third direction D3. It is also noted that organic light emittingdiode 503 is connected to pixel circuit 501. As seen in FIG. 5, pixelcircuit 501 includes driving thin film transistor (TFT) 505, switchingTFT 507, and storage capacitor 509. Although reference will be made tothis implementation, it is also contemplated that pixel circuit 501 mayembody many forms and include multiple and/or alternative components andconfigurations. For instance, pixel circuit 501 may include any suitablenumber of thin film transistors and any suitable number of storagecapacitors. As such, the equivalent circuit diagram of FIG. 5 is merelyillustrative; exemplary embodiments are not limited thereto or thereby.In this manner, any suitable pixel circuit may be utilized inassociation with exemplary embodiments.

In one or more exemplary embodiments, switching TFT 507 includes a firstelectrode connected to gate line GL, a second electrode connected todata line DL, and a third electrode connected to a first electrode ofstorage capacitor 509 and a first electrode of driving TFT 505. In thismanner, switching TFT 507 is configured to transfer a data signal Dmreceived via data line DL to driving TFT 505 in response to a scansignal Sn received via gate line GL. As previously mentioned, the firstelectrode of storage capacitor 509 is connected to the third electrodeof switching TFT 507. A second electrode of storage capacitor 509 isconnected to driving voltage line DVL and a second electrode of drivingTFT 505. As such, storage capacitor 509 is configured to store a voltagecorresponding to a difference between a voltage received via switchingTFT 507 and a driving voltage ELVDD received via driving voltage lineDVL.

The second electrode of driving TFT 505 is connected to driving voltageline DVL and the second electrode of storage capacitor 509. Driving TFT505 also includes a first electrode connected to the third electrode ofswitching TFT 507 and a third electrode connected to a first electrodeof organic light emitting diode 503. In this manner, driving TFT 505 isconfigured to control a driving current through organic light emittingdiode 503 from driving voltage line DVL in response to the voltage valuestored in storage capacitor 509. The organic light emitting diode 503includes a first electrode connected to the third electrode of drivingTFT 505 and a second electrode connected to common power voltage 511,e.g., a common power voltage ELVSS. As such, organic light emittingdiode 503 may emit light at a determined brightness (and, in one or moreexemplary embodiments, a determined color) according to the drivingcurrent received via driving TFT 505.

According to one or more exemplary embodiments, driving TFT 505 andswitching TFT 507 may each include an active layer (not shown) disposedin association with the various electrodes of the corresponding thinfilm transistor. The active layer may be formed of any suitablesemiconductor material. For example, the active layer may contain aninorganic semiconductor material, such as amorphous silicon orpolysilicon crystallized from amorphous silicon. The active layer maycontain an oxide semiconductor material, such as an oxide of a materialselected from a group XII, XIII, or XIV element, such as zinc (Zn),indium (In), gallium (Ga), tin (Sn), cadmium (Cd), germanium (Ge), andhafnium (Hf), or combinations thereof. It is also noted that the activelayer may be formed of a relatively low polymer-series or polymer-seriesorganic material, such as mellocyanine, phthalocyanine, pentacene,thiophen, etc.

Although not illustrated, organic light emitting diode 503 may include apixel electrode, an opposite electrode, and an intermediate layerdisposed between the pixel electrode and the opposite electrode. Theintermediate layer is configured to emit light according to a voltagedifference across the pixel electrode and the opposite electrode. Inthis manner, the pixel electrode may function as the above-noted firstelectrode (e.g., an anode electrode) of organic light emitting diode503, and the opposite electrode may function as the above-noted secondelectrode (e.g., cathode electrode) organic light emitting diode 503. Itis contemplated, however, that the polarities of the pixel electrode andthe opposite electrode may be reversed.

According to one or more exemplary embodiments, the pixel electrode andthe opposite electrode are insulated from each other via theintermediate layer. An organic emission layer of the intermediate layermay emit light according to voltages of different polarities beingapplied to the intermediate layer. In this manner, the intermediatelayer may include an organic emission layer. As another example, theintermediate layer may include the organic emission layer, and furtherinclude at least one layer selected from the group consisting of a holeinjection layer (HIL), a hole transport layer (HTL), an electrontransport layer (ETL), and an electron injection layer (EIL).

Although a light emitting material may be separately included inrespective pixels PXL of the above-noted organic light emission layer,exemplary embodiments are not limited thereto or thereby. For example,the organic light emission layer may be a common organic light emissionlayer used for each pixel PXL regardless of its location. In one or moreexemplary embodiments, the organic light emission layer may includelight emitting materials to respectively emit red light, green light,and blue light, however, any other suitable color may be utilized inassociation with exemplary embodiments. The light emitting materials maybe stacked in a vertical direction or disposed in a mixed manner. Thelight emitting materials may include materials to emit a combination ofdifferent colors. The combination of different colors may be utilized toform white light. Although not illustrated, a color conversion layer ora color filter may be included to convert the emitted white light to acertain color.

Adverting back to FIGS. 1-3 and 4A, flexible display panel 100 mayfurther include supporting layer BF, which may be coupled to (or formedon) flexible substrate TFS after a carrier substrate (not shown) isremoved as part of manufacturing flexible display panel 100. Anexemplary process of forming flexible display panel 100 includingutilization of a carrier substrate will be described in more detail inassociation with FIG. 6. Supporting layer BF may be formed of athermoplastic material, such as a thermoplastic resin, however,exemplary embodiments are not limited thereto or thereby. In otherwords, supporting layer BF may be formed of any suitable material. Forinstance, supporting layer BF may be formed of polyethylene (PE),polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride(PVC), polyethylene naphthalate (PEN), etc. As such, supporting layer BFmay exhibit a melting point, as well as a decomposition point. Forinstance, supporting layer BF may be formed of PET exhibiting a meltingpoint around 250° C. and a decomposition temperature around 350° C. Inthis manner, the material configuration of supporting layer BF mayexhibit a lower melting and/or sublimating temperature than a materialconfiguration of flexible substrate TFS. It is also noted thatsupporting layer BF may be coupled to flexible substrate TFS via anysuitable technique, whether mechanical, chemical, etc. For example,supporting layer BF may be coupled to flexible substrate TFS viaoptically clear adhesive (OCA), pressure sensitive adhesive (PSA),and/or the like.

According to one or more exemplary embodiments, supporting layer BF mayinclude a first portion exhibiting first material properties and asecond portion exhibiting second material properties, as will becomemore apparent below. The differences in material properties may be theresult of thermally deforming a portion of supporting layer BF inassociation with one or more exemplary embodiments described herein. Ingeneral, however, it is noted that the differences in materialproperties between the first and second portions of supporting layer BFmay relate to differences in density, hardness, surface roughness,color, etc. Further, the first and second portions of supporting layerBF may be different based on the presence of a charred surface, trappedbubbles (e.g., air bubbles), etc. Apart from differences in materialproperties, the first and second portions of supporting layer BF may bedimensionally different.

For example, as seen in FIGS. 3 and 4A, a thickness of supporting layerBF may be smaller (e.g., thinned) in supporting layer portion ABF, whichmay be omitted. When supporting layer portion ABF is omitted, firstsurface TFSa of flexible substrate TFS may be exposed in a portion ofsupporting layer BF that would otherwise correspond to supporting layerportion ABF. It is also noted that supporting layer portion ABF maycorrespond to or include a portion of supporting layer BF in which atleast one material property of supporting layer BF has been modifiedvia, for instance, thermal deformation, as will become more apparentbelow.

According to one or more exemplary embodiments, one or more of first tofourth non-display areas NDA1 to NDA4 (e.g., second non-display areaNDA2) may be bent from plane PL tangent to a surface of display panellayer DP to, for example, enhance aesthetics of flexible display panel100 when incorporated as part of an electronic device. In this manner, aportion of bent non-display areas (e.g., a portion of second non-displayarea NDA2) may be bent, such as about bending axis BX and under displaypanel layer DP to reduce a size and exposure of the non-display areawhen first surface SF1 of flexible display panel 100 is viewed in a planview. For instance, a size and exposure of portion PA1 may be reduced bybending second non-display area NDA2 with respect to bending axis BX andplane PL. It is noted, however, that flexible display panel 100 may bebent at angles greater than 0 degrees and less than or equal to 360degrees, e.g., at angles greater than 0 degrees and less than or equalto 270 degrees. Further, although only second non-display area NDA2 isillustrated as being bent, it is contemplated that one or more of firstto fourth non-display areas NDA1 to NDA4 may be bent to reduce theirrespective sizes. To this end, a portion of display area DA may be bentin association with the bending of at least one of first to fourthnon-display areas NDA1 to NDA4. In this manner, flexible display panel100 may be bent to include a curved surface portion.

According to one or more exemplary embodiments, modification ofsupporting layer BF (e.g., via thermal deformation, via thermaldeformation and dimensional alteration, etc.) may be utilized to reducethe amount of force to bend a non-display area of flexible display panel100, and, thereby, to reduce the amount of stress generated when thenon-display area is bent from plane PL. In this manner, reduction of thestress may reduce degradation of the structural integrity (e.g., reducethe potential for cracks, etc.) and performance (e.g., reduce thepotential for increases in resistivity, etc.) of signal lines SLextending between pixels PXL and at least one of flexible printedcircuit board FPCB and integrated circuit IC. Reduction of the stressmay also enable a size of bending radius R of flexible display panel 100to be reduced, and, thereby, enable an overall thickness of anelectronic device incorporating flexible display panel 100 to bereduced. For instance, bending radius R may be greater than or equal totwice the aggregate thickness of flexible substrate TFS and supportinglayer BF and less than or equal to 0.3 mm. Larger bending radii,however, may be utilized with exemplary embodiments.

Various techniques to modify features of supporting layer BF may beutilized, such as described in association with FIGS. 6, 7, 8A-8D,9A-9C, 11, 12A, 12B, 13A-13C, 14A, 14B, 15A, 15B, 16A, 16B, 17, 18A, and18B. In at least one of these techniques, a component utilized toeffectuate the modification of the feature(s) of supporting layer BF mayremain part of flexible display panel 100, such as described inassociation with FIG. 4B.

FIG. 4B is a cross-sectional view of the flexible display panel of FIG.1 taken along sectional line III-III′ in a second bent state, accordingto one or more exemplary embodiments. Flexible display panel 100′ issimilar to flexible display panel 100 of FIGS. 1-3 and 4A, and, as such,duplicative descriptions are primarily omitted to avoid obscuringexemplary embodiments.

As seen in FIG. 4B, supporting layer BF′ includes wire W disposed insupporting layer portion ABF′. According to one or more exemplaryembodiments, wire W may become part of flexible display panel 100′ as aresult of pressing wire W into a surface of supporting layer BF′ tothermally deform a portion of supporting layer BF′. It is alsocontemplated that supporting layer BF′ may be patterned, thermallyconductive material may formed in patterned regions of supporting layerBF′, and the thermally conductive material in the patterned regions maybe heated to effectuate thermal deformation of supporting layer BF′. Aswill become more apparent below, wire W may be heated to alter aproperty of supporting layer BF′, and, thereby, to facilitate bending offlexible display panel 100 with less force than would otherwise berequired. Further, supporting layer portion ABF′ may cover flexiblesubstrate TFS, and, as such, surface ABFa′ may be exposed instead offirst surface TFSa of flexible substrate TFS.

With reference to FIGS. 4A and 4B, flexible display panels 100 and 100′may include bending protection layer BPL on a curved surface portion offlexible substrate TFS to protect the curved surface portion from, forexample, external forces, impacts, effects of later occurringmanufacturing processes, etc. It is noted, however, that bendingprotection layer BPL is optional, and, therefore, may be omitted. Forinstance, supporting layer portion ABF may sufficiently support andprotect the structural integrity of the curved surface portion offlexible display panel 100, and, as such, bending protection layer BPLmay be omitted. When utilized in association with supporting layerportion ABF, a thickness of bending protection layer BPL may be reduced,which may also reduce manufacturing costs and time. In one or moreexemplary embodiments, a thickness of bending protection layer BPL maybe greater than a thickness of display panel layer DP, however,exemplary embodiments are not limited thereto or thereby.

FIG. 6 is a flowchart of a process for forming a flexible display panelwith at least one bent portion, according to one or more exemplaryembodiments. The process of FIG. 6 will be described in association withFIGS. 1, 3, 4A, and 5. It is noted that the process of FIG. 6 will alsobe described in association with bending second non-display area NDA2,however, it is contemplated that one or more of first to fourthnon-display areas NDA1 to NDA4 may be bent in association with exemplaryembodiments.

In step 601, one or more display structures, such as thin-filmtransistor structures, storage capacitor structures, organiclight-emitting diode structures, gate lines GL, data lines DL, datavoltage lines DVL, signal lines SL, and the like, may be formed onflexible substrate TFS, which may be a polyimide layer attached to acarrier substrate (not shown), such as a glass carrier substrate. Inthis manner, flexible display panel 100 may be partially formedincluding display area DA and first to fourth non-display areas NDA1 toNDA4. At step 603, one or more integrated circuits (e.g., integratedcircuit IC), which may include at least one driver configured to cause,at least in part, pixels PXL to display an image, may be coupled toflexible substrate TFS. For instance, integrated circuit IC may becoupled to flexible substrate TFS in second non-display area NDA2. Theglass carrier substrate may be removed, e.g., delaminated, from flexiblesubstrate TFS, per step 605. At step 607, supporting layer BF may beattached to flexible substrate TFS via, for instance, an OCA, a PSA,and/or the like. In step 609, flexible printed circuit board FPCB may becoupled to flexible substrate TFS via conductive adhesive.

According to one or more exemplary embodiments, a first portion ofsecond non-display area NDA2 may be thermally deformed, per step 611.Thermal deformation of the first portion of second non-display area NDA2may cause, at least in part, at least one property of the material ofsupporting layer BF to be altered in at least the first portion. Forexample, thermal deformation of the first portion of second non-displayarea NDA2 may cause, at least in part, a change in density, hardness,surface roughness, color, and/or the like, in at least the first portionof second non-display area NDA2. To this end, thermal deformation of thefirst portion may also cause, at least in part, a dimensional change tosupporting layer BF in at least the first portion of second non-displayarea NDA2. In step 613, a second portion of second non-display area NDA2that extends from the first portion of second non-display area NDA2 isbent with respect to display area DA. For example, the second portion ofsecond non-display area NDA2 may be bent with respect to plane PLtangent to a surface of display area DA. To this end, the second portionof second non-display area NDA2 may be bent about bending axis BX, suchthat at least some of second non-display portion NDA2 is disposed underdisplay area DA.

To reduce mechanical stress in flexible display panel 100 when, forinstance, the second portion of second non-display area NDA2 is bentfrom display area DA, one or more techniques may be employed, e.g.,“hot” bending techniques, “hot” bending and notching techniques, etc.For instance, flexible display panel 100 may be “hot” bent via a hotwire bending technique, described in more detail in association withFIGS. 7, 8A-8D, 9A-9C, and 10.

FIG. 7 is a flowchart of a process for bending a flexible display panelvia a hot wire bending technique, according to one or more exemplaryembodiments. FIGS. 8A, 8B, 8C, and 8D are partial perspective views of aflexible display panel at various stages of being bent via a hot wirebending technique, according to one or more exemplary embodiments. FIGS.9A, 9B, and 9C are partial cross-sectional views of various hot wireconfigurations, according to one or more exemplary embodiments. FIG. 10illustrates material property alterations in a layer of a flexibledisplay panel caused, at least in part, by a hot wire bending technique,according to one or more exemplary embodiments.

At step 701, wire W is prepared for “hot” wire bending of flexibledisplay panel 100. For example, a temperature of wire W is tensioned,elevated close to a melting temperature of a material of supportinglayer BF, and positioned with respect to supporting layer BF, as seen inFIG. 8A. In one or more exemplary embodiments, the temperature of wire Wis elevated only so high as to ensure the structural integrity of wire Wwhen held under a modest amount of tension, such as greater than orequal to 1 N and less than or equal to 3 N, at an elevated temperature.In this manner, wire W may be formed of tungsten, however, any suitablethermally conductive material capable of being tensioned as previouslymentioned at elevated temperatures may be utilized in associationexemplary embodiments. When, for instance, supporting layer BF is formedof PET with a glass transition temperature around 76° C., a meltingtemperature around 250° C., and a decomposition temperature around 350°C., the temperature of wire W may be greater than or equal to 76° C. andless than or equal to 250° C. When the temperature of wire W is lessthan 76° C., the material of supporting layer BF may not transition intoa liquid phase when wire W is disposed on (e.g., pressed against)supporting layer BF. When the temperature of wire W is greater than 250°C., the structural integrity of wire W may be compromised and break. Itis also noted that when the temperature of wire W is greater than 250°C., at least one other component of flexible display panel 100 may bedamaged. This may compromise the structural integrity of flexibledisplay panel 100, as well as introduce at least one defect affectingdisplay quality.

According to one or more exemplary embodiments, flexible substrate TFSmay be formed of polyimide having a decomposition temperature around452° C. when heat is applied continuously and a decompositiontemperature around 704° C. when heat is applied in relatively shortbursts of time. In this manner, polyimide may be considered a thermosetmaterial that does not generally melt, but may decompose if sufficientamount of heat is applied. Given that polyimide does not generally melt,a melting point of supporting layer BF may be lower than a melting pointof flexible substrate TFS. As such, the material composition of flexiblesubstrate TFS may be selected to prevent or at least reduce thepotential of damage to at least one other component of flexible displaypanel 100 when the temperature of wire W is greater than 250° C. orsupporting layer BF is removed and wire W interfaces with flexiblesubstrate TFS.

In step 703, wire W is disposed on supporting layer BF. For instance,wire W is held under tension at an elevated temperature and pressed intosupporting layer BF in the first portion of second non-display areaNDA2, as seen in FIG. 8B. According to step 705, a material ofsupporting layer BF is thermally deformed, e.g., the material ofsupporting layer BF at least transitions from a solid phase to a liquidphase. That is, some material of the first portion of supporting layerBF melts. As a result of the melting, at least one material property ofthe some material of the first portion of supporting layer BF ismodified. For instance, as seen in FIG. 10, bubbles (e.g., air bubbles)may be formed in the first portion of supporting layer BF, surfaceroughness of supporting layer BF may be modified, density of supportinglayer BF may be changed, bumps in edges of supporting layer BF may beformed, traces of burns in surfaces of supporting layer BF may beidentifiable, etc. It is also noted that the thermal deformation maycause, at least in part, hardness of a portion of supporting layer BF tobe modified relative to other portions of supporting layer BF.

According to one or more exemplary embodiments, the thermal deformationof the first portion of supporting layer BF is also accompanied bydimensional changes in the first portion of supporting layer BF. Forinstance, wire W may move material from the first portion of supportinglayer BF into another portion of supporting layer BF. This may formsupporting layer portion ABF and/or remove supporting layer BF in aregion where wire W is pressed into supporting layer BF. As can beappreciated by comparing FIGS. 9A and 9B, the dimensional changes insupporting layer portion ABF are less than dimensional changes insupporting layer portion ABF₂. This difference in dimensional change maybe associated with a depth at which wire W is pressed into supportinglayer BF and an amount of material of the first portion of secondnon-display area NDA2 is permitted to be displaced before the materialtransitions back into a solid phase. Further, the cross-sectional shapeof wire W may be modified (that may also modify formation of supportinglayer portion ABF), as can be appreciated from wire W₂ and supportinglayer portion ABF₃ in FIG. 9C.

At step 707, a second portion of second non-display area NDA2 is bentwith respect to display area DA, as seen in FIG. 8B. In one or moreexemplary embodiments, the second portion of second non-display areaNDA2 is bent such that surfaces of supporting layer BF oppose oneanother, as seen in FIG. 8C. It is noted that the second portion ofsecond non-display area NDA2 may be bent while wire W is pressed intosupporting layer BF or may be bent after removing wire W from supportinglayer BF. According to one or more exemplary embodiments, the secondportion of second non-display area NDA2 is bent within a determined timeperiod of thermally deforming the first portion of second non-displayarea NDA2. For example, the second portion of second non-display areaNDA2 is bent within 1 to 2 seconds of thermally deforming the firstportion of second non-display area NDA2 or within 1 to 2 seconds ofremoving wire W from supporting layer BF. As seen in FIGS. 8B and 8C,the second portion of second non-display area NDA2 is bent while wire Wis pressed into supporting layer BF.

In one or more exemplary embodiments, it is determined, per step 709,whether wire W is to be removed from flexible display panel 100. Thatis, whether wire W is to be removed from supporting layer BF after orwhile the second portion of second non-display area NDA2 is being bent.When wire W remains a part of flexible display panel 100, portions ofwire W extending beyond lateral side surfaces of flexible display panel100 may be cut from flexible display panel 100, in step 711. In thoseinstances when wire W is to be removed, wire W is displaced from thefirst portion of second non-display area NDA2 and removed from flexibledisplay panel 100, per step 713. As seen in FIG. 8D, wire W is removedfrom flexible display panel 100, such that trench G is formed. It isnoted that surfaces of trench G may exhibit differences in surfaceroughness relative to other portions of supporting layer BF, as well asexhibit traces of burns, e.g., may appear to be charred, relative to theother portions of supporting layer BF. To this end, bubbles may betrapped near the surfaces of trench G.

According to one or more exemplary embodiments, flexible display panel100 may be “hot” bent via a hot press bending technique, which isdescribed in more detail in association with FIGS. 11, 12A, 12B,13A-13C, 14A, 14B, 15A, and 15B. For instance, the second portion ofsecond non-display area NDA2 may be bent from display area DA offlexible display panel 100 according to at least one hot press bendingtechnique, e.g., at least one of the hot press bending techniques ofFIGS. 11, 12A, 12B, 13A-13C, 14A, 14B, 15A, and 15B.

FIG. 11 is a flowchart of a process for bending a flexible display panelvia a hot press bending technique, according to one or more exemplaryembodiments. FIGS. 12A and 12B schematically illustrate various stagesof a hot press bending technique, according to one or more exemplaryembodiments. FIGS. 13A, 13B, and 13C schematically illustrate varioushot press configurations, according to various exemplary embodiments.FIGS. 14A, 14B, 15A, and 15B schematically illustrate flexible displaypanels at various stages of hot press bending techniques, according tovarious exemplary embodiments.

In step 1101, stamping tool 1201 is positioned over the first portion ofsecond non-display area NDA2 of flexible display panel 100, as seen inFIG. 12A. In one or more exemplary embodiments, supporting layer BF mayface stamping tool 1201. That is, supporting layer BF may be disposedbetween stamping tool 1201 and flexible substrate TFS. It is noted thatsupporting layer BF may be formed of PET having a glass transitiontemperature around 76° C., a melting temperature around 250° C., and adecomposition temperature around 350° C. To this end, flexible substrateTFS may be formed of PI having a decomposition temperature around 452°C. when heat is applied continuously and a decomposition temperaturearound 704° C. when heat is applied in relatively short bursts of time.

As seen in FIG. 12A, stamping tool 1201 at least includes portion 1203extending from main body portion 1205. Main body portion 1205 is formedof any suitable material composition configured to withstandtemperatures greater than or equal to the decomposition temperature ofthe material composition of supporting layer BF and less than or equalto the decomposition temperature of the material composition of flexiblesubstrate TFS. For instance, main body portion 1205 may be configured towithstand temperatures greater than or equal to 350° C., such as greaterthan or equal to 350° C. and less than or equal to 700° C., e.g.,greater than or equal to 350° C. and less than or equal to 450° C.Although not illustrated in FIG. 12A, main body portion 1205 may extend(e.g., longitudinally extend) in second direction D2 to stamp a portionof supporting layer BF overlapping bending axis BX illustrated in FIGS.1 and 2.

According to one or more exemplary embodiments, main body portion 1205may include and be configured to transfer thermal energy to at least onethermal concentration portion configured to concentrate thermal energyreceived from main body portion 1205. For example, stamping tool 1301includes quadrilateral thermal concentration portion 1303, as seen inFIG. 13A. FIG. 13B illustrates stamping tool 1305 including generallyhemispherical concentration portion 1307, whereas FIG. 13C illustratesstamping tool 1309 including an array of triangular thermalconcentration portions 1311. It is contemplated, however, that anysuitable arrangement, configuration, and number of thermal concentrationportions may be utilized. To this end, it is noted that the shape ofmain body portion 1205, the shape of thermal concentration portions, andthe number of thermal concentration portions may be modified to achievedifferent bending radii of the second portion of second non-display areaNDA2. In other words, different configurations of stamping tool 1201 maybe utilized to alter the amount of stress reduction in flexible displaypanel 100 when flexible display panel 100 is bent about bending axis BX.

At step 1103, the temperature of main body portion 1205 of stamping tool1201 is elevated. When the stamping tool includes at least one thermalconcentration portion, elevation of the temperature of main body portion1205 will cause thermal energy to be concentrated in the at least onethermal concentration portions. In one or more exemplary embodiments,the temperature of main body portion 1205 is elevated greater than orequal to the decomposition temperature of the material composition ofsupporting layer BF and less than or equal to the decompositiontemperature of the material composition of flexible substrate TFS, suchas greater than or equal to 350° C. and less than or equal to 700° C.,e.g., greater than or equal to 350° C. and less than or equal to 450°C., for instance, 400° C. When the temperature of main body portion lessthan the decomposition temperature of the material composition ofsupporting layer BF, sublimation of at least one portion of secondnon-display area NDA2 may not be achieved. When the temperature of mainbody portion 1205 is greater than the decomposition temperature of thematerial composition of flexible substrate TFS, at least one othercomponent of flexible display panel 100 may be damaged, such as flexiblesubstrate TFS. This may compromise the structural integrity of flexibledisplay panel 100, as well as introduce at least one defect affectingdisplay quality.

In step 1105, stamping tool 1201 is disposed on supporting layer BF. Forinstance, stamping tool 1201 is held at an elevated temperature andpressed into supporting layer BF in the first portion of secondnon-display area NDA2, as seen in FIG. 12B. According to step 1107, amaterial of supporting layer BF is thermally deformed, e.g., thematerial of supporting layer BF at least transitions into a gaseousphase. That is, some material of the first portion of supporting layerBF sublimates. As a result of the sublimation, at least one trench isformed in the first portion of supporting layer BF and at least onematerial property of other material disposed relatively closer tosurfaces of the at least one trench is modified.

For instance, as seen in FIGS. 14A and 14B, trenches 1401 and 1501 maybe formed and bubbles (e.g., air bubbles) 1403 and 1503 may be trappedrelatively closer to surfaces of trenches 1401 and 1501 than otherportions of supporting layer BF. As seen in FIG. 14A, trench 1401exposes first surface TFSa of flexible substrate TFS opposing secondsurface TFSb of flexible substrate TFS. In FIG. 15A, formation of trench1501 via stamping tool 1201 enables formation of supporting layerportion ABF including surface ABFa opposing second surface TFSb offlexible substrate TFS. Although not shown in FIGS. 14A and 14B,sublimation of the some material of the first portion of supportinglayer BF may also cause, at least in part, surface roughness of aportion of supporting layer BF to be modified, density of a portion ofsupporting layer BF to be changed, bumps in edges of a portion ofsupporting layer BF to be formed, color differences in a portion ofsupporting layer BF to be generated, etc. It is also noted that thethermal deformation may cause, at least in part, hardness of a portionof supporting layer BF to be modified relative to other portions ofsupporting layer BF.

At step 1109, stamping tool 1201 is removed from the first portion ofsecond non-display area NDA2, as seen in FIGS. 14A and 14B. Within adetermined period of time of thermally deforming the first portion ofsecond non-display area NDA2, a second portion of second non-displayarea NDA2 is bent with respect to display area DA of flexible displaypanel 100, per step 1111. For example, the second portion of secondnon-display area NDA2 is bent within 1 to 2 seconds of thermallydeforming the first portion of second non-display area NDA2 or within 1to 2 seconds of removing stamping tool 1201 from supporting layer BF. Asseen in FIGS. 14B and 15B, cavity regions 1405 and 1505 may be formed inassociation with bending the second portion of second non-display areaNDA2. Although FIGS. 14B and 15B illustrate bending radii in whichopposing surfaces of supporting layer BF are not in contact with oneanother, it is contemplated that opposing surfaces of supporting layerBF may be in contact. As such, a bending radius of flexible displaypanel 100 may be greater than or equal to twice the thickness ofsupporting layer BF, such as greater than or equal to about 200 μm.Larger bending radii may be formed in association with exemplaryembodiments.

According to one or more exemplary embodiments, at least one of the hotwire and hot press bending techniques may be utilized to form a patternof thermal deformations in support layer BF that may further reducemechanical stress on flexible display panel 100 when flexible displaypanel 100 is bent. An exemplary pattern of thermal deformations toflexible display panel 100 is described in more detail in associationwith FIGS. 16A and 16B.

FIGS. 16A and 16B schematically illustrate a flexible display panel atvarious stages of being bent, according to one or more exemplaryembodiments.

As seen in FIG. 16A, a pattern of thermal deformations (e.g., a patternof trenches G₁ to G_(n), n being a natural number greater than 1) areformed in supporting layer portion ABF₄ of a flexible display panel,such as flexible display panel 100 of FIG. 1. Each trench may exhibit amaximum length in first direction D1 of G_(L). To this end, supportinglayer portion ABF₄ includes a length L, and an aggregate thickness ofthe flexible display panel in association with supporting layer portionABF₄ is d. In one or more exemplary embodiments, removal of material ofsupporting layer portion ABF₄ enables the flexible display device to bemore easily bent at least because less material is structurally deformedand because the bending of the flexible display device occurs while thetemperature of supporting layer portion ABF₄ is raised.

Referring to FIG. 16B, bending of the flexible display panel may causeat least some of trenches G₁ to G_(n) to close, such that length L₁ ofsecond surface TFS_(b) of flexible substrate TFS is longer than lengthL₂ of surface ABFa of supporting layer portion ABF₄. For instance,length L₁ may be determined according to Equation 1, whereas length L₂may be determined according to Equation 2.L ₁=2/(2π(R+d))  Eq. 1L ₂=2/(2πR)=L ₁ −nG _(L)  Eq. 2

It is noted that L₁=the length of second surface TFSb of flexiblesubstrate TFS; L₂=the length of surface ABFa of supporting layer portionABF4; R=the bend radius of the flexible display device; G_(L)=trenchwidth in first direction D1; n=the number of trenches formed insupporting layer portion ABF4; and d=the aggregate thickness of flexiblesubstrate TFS and supporting layer portion ABF₄.

To reduce mechanical stress in flexible display panel 100 when, forinstance, the second portion of second non-display area NDA2 is bentfrom display area DA, a “notching” technique may be may be employed toremove material in a first portion of second non-display area NDA2. Itis noted that the “notching” technique may also heat a third portion ofsupporting layer BF to enable opposing surfaces of supporting layer BFto be coupled together without use of a separate adhesive component,such as a separate OCA, PSA, etc. An exemplary “notching” technique isdescribed in more detail in association with FIGS. 17, 18A, and 18B.

FIG. 17 is a flowchart of a process for bending a flexible displaypanel, according to one or more exemplary embodiments. FIGS. 18A and 18Bschematically illustrate a flexible display panel at various stages ofbeing bent, according to one or more exemplary embodiments.

In step 1701, cutting tool 1801 is positioned over the first portion ofsecond non-display area NDA2 of flexible display panel 100. In one ormore exemplary embodiments, supporting layer BF may face cutting tool1801. That is, supporting layer BF may be disposed between cutting tool1801 and flexible substrate TFS. It is also noted that supporting layerBF may be formed of PET having a glass transition temperature around 76°C., a melting temperature around 250° C., and a decompositiontemperature around 350° C. To this end, flexible substrate TFS may beformed of PI having a decomposition temperature around 452° C. when heatis applied continuously and a decomposition temperature around 704° C.when heat is applied in relatively short bursts of time.

At step 1703, cutting tool 1801 is manipulated to remove some materialfrom the first portion of second non-display area NDA2, as seen in FIG.18A. For instance, cutting tool 1801 may include cutting wheel 1803supported via one or more articulations (e.g., articulations 1805, 1807,and 1809) that may be connected to one another via one or more joints(e.g., joints 1811 and 1813). In this manner, manipulation of the one ormore articulations, the one or more joints, and cutting wheel 1803 mayenable trench 1815 to be formed in supporting layer BF. To this end,formation of trench 1815 may or may not expose first surface TFSa offlexible substrate TFS. As seen in FIG. 18A, supporting layer portionABF₅ is formed, such that first surface TFSa is not exposed, butinstead, is covered by supporting layer portion ABF₅ including surfaceABF₅ a opposing first surface TFSa of flexible substrate TFS.

Manipulation of cutting tool 1801 may cause one or more third portionsHBF of supporting layer BF to be heated, per step 1705. For instance,rotation of articulation 1805 to rotate cutting wheel 1803 may causethird portion HBF to heat according to friction between supporting layerBF and articulation 1805. Heating of third portion HBF may transition atleast some of the material of third portion HBF to a liquid phase, aswell as thermally deform at least some of third portion HBF. As a resultof the thermal deformation, at least one material property of the somematerial of the third portion HBF may be modified, such as previouslydescribed in association with FIGS. 7 and 10. It is also noted that thethermal deformation may cause, at least in part, hardness of a portionof supporting layer BF to be modified relative to other portions ofsupporting layer BF.

In step 1707, cutting tool 1707 is repositioned to enable a secondportion of second non-display area NDA2 to be bent. At step 1709, thesecond portion of second non-display area NDA2 is bent with respect todisplay area DA, as seen in FIG. 18B. In one or more exemplaryembodiments, the second portion of second non-display area NDA2 is bentsuch that surfaces of supporting layer BF oppose one another and contactone another. According to one or more exemplary embodiments, the secondportion of second non-display area NDA2 is bent within a determined timeperiod of thermally deforming third portion HBF of second non-displayarea NDA2. For example, the second portion of second non-display areaNDA2 is bent within 1 to 2 seconds of thermally deforming third portionHBF or within 1 to 2 seconds of repositioning cutting tool 1801. As seenin FIG. 18B, cavity region 1817 may be formed in association withbending the second portion of second non-display area NDA2. As such, abending radius of the flexible display panel may be greater than orequal to twice the thickness of supporting layer BF, such as greaterthan or equal to about 200 μm. It is noted, however, that larger bendingradii may be formed in association with exemplary embodiments.

As previously mentioned, bending of the second portion of secondnon-display area NDA2 causes surfaces of supporting layer BF to opposeand contact one another. Given that bending occurs relatively shortlyafter elevating the temperature of third portion HBF, then thecontacting surfaces of supporting layer HBF may be coupled to oneanother as third portion HBF cools, per step 1711. In other words, theliquid phase of third portion HBF may solidify to couple contactingsurfaces of supporting layer BF to one another. As such, a separateadhesive component, e.g., an OCA, a PSA, etc., may be omitted. Moreover,given that bending occurs relatively shortly after elevating thetemperature of third portion HBF and given the presence of trench 1815,the flexible display panel may be bent with less force than wouldotherwise be required, and, as such, less stress is generated.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concept is not limitedto such embodiments, but rather to the broader scope of the presentedclaims and various obvious modifications and equivalent arrangements.

What is claimed is:
 1. A flexible display panel comprising: a displayarea to display an image; and a non-display area disposed outside thedisplay area, wherein the non-display area comprises: a first portionextending from the display area, the first portion comprising a supportlayer disposed on a flexible substrate; and a second portion extendingfrom the first portion, the second portion being bent from a plane ofthe first portion, and wherein a property of a material of the supportlayer in the first portion is different than the property of thematerial of the support layer in the second portion.
 2. The flexibledisplay panel of claim 1, wherein the property corresponds to at leastone of a density of the material, a hardness of the material, a surfaceroughness of the material, and a color of the material.
 3. The flexibledisplay panel of claim 1, wherein the second portion comprises at leastone of a charred surface and trapped bubbles.
 4. The flexible displaypanel of claim 1, wherein: the second portion comprises the flexiblesubstrate and some of the support layer; and a material of the flexiblesubstrate is different than the material of the support layer.
 5. Theflexible display panel of claim 4, wherein a melting point of thematerial of the flexible substrate is greater than a melting point ofthe material of the support layer.
 6. The flexible display panel ofclaim 4, wherein: the material of the support layer comprisespolyethylene terephthalate; and the material of the flexible substratecomprises polyimide.
 7. The flexible display panel of claim 1, whereinthe material of the support layer comprises a thermoplastic material. 8.The flexible display panel of claim 1, wherein: the second portioncomprises a conductive line disposed therein; and an altered property ofthe material of the support layer is disposed relatively closer to theconductive line than other areas of the second portion.
 9. The flexibledisplay panel of claim 1, wherein: the second portion comprises atrench; and an altered property of the material of the second layer isdisposed relatively closer to a surface of the trench than other areasof the second portion.
 10. The flexible display panel of claim 9,wherein: the trench extends towards a first surface of the flexiblesubstrate.
 11. The flexible display panel of claim 10, wherein thetrench exposes the first surface of the flexible substrate.
 12. Theflexible display panel of claim 10, wherein: the trench is one of aplurality of “n” trenches; a width of each trench of the plurality of“n” trenches is “G_(L)”; a bend radius of the second portion is “R”; alength of a second surface of the flexible substrate is “L₁”, the secondsurface opposing the first surface of the flexible substrate; athickness of the support layer is “d”; a length of the first surface ofthe flexible substrate is L₂; andL ₂=2/(2πR)=L ₁ −nG _(L).
 13. The flexible display panel of claim 1,wherein a bend radius of the second portion is greater than or equal toa thickness of the first portion and less than or equal to 0.35 mm. 14.The flexible display panel of claim 1, wherein a thickness of the secondportion varies with increasing distance from an apex of the bend.
 15. Aflexible apparatus comprising: an active area; and an inactive areadisposed outside the active area, wherein the inactive area comprises: afirst portion extending from the active area, the first portioncomprising a support layer disposed on a flexible substrate; and asecond portion extending from the first portion, the second portionbeing bent from a plane of the first portion, and wherein a property ofa material of the support layer in the first portion is different thanthe property of the material of the support layer in the second portion.16. The flexible apparatus of claim 15, wherein the active areacorresponds to a display area of the flexible apparatus.
 17. Theflexible apparatus of claim 15, wherein the active area corresponds to atouch sensitive area of the flexible apparatus.
 18. A flexible apparatuscomprising: a first area; and a second area disposed outside the firstarea, wherein the second area comprises: a first portion extending fromthe first area, the first portion comprising a support layer disposed ona flexible substrate; and a second portion extending from the firstportion, the second portion being bent from a plane tangent to a surfaceof the first portion, and wherein a property of a material of thesupport layer in the first portion is different than the property of thematerial of the support layer in the second portion.
 19. The flexibleapparatus of claim 18, wherein the first portion is a planar portion.20. The flexible apparatus of claim 18, wherein the first portion isbent from a plane of the first area.
 21. The flexible apparatus of claim18, wherein the first area is a touch detection area of the flexibleapparatus.
 22. The flexible apparatus of claim 18, wherein the firstarea is a display area of the flexible apparatus.